Hepcidin Inhibition by Modified Heparins without Anticoagulant Activity

There is an increasing interest in the development of pharmacological agents able to modulate hepcidin, the peptide hormone that critically regulates iron metabolism. In particular, hepcidin antagonist may have a therapeutic role in the anemia of chronic diseases, where hepcidin levels are often increased by pro-inflammatory cytokines. We previously demonstrated that heparin is a potent inhibitor of hepcidin expression in hepatic cell lines, probably by interfering with BMP/HJV/SMAD signalling, and that it was also effective in reducing hepcidin expression in mice (Poli M, Blood 2011; 117:997–1004). Since the therapeutic use of heparin for hepcidin modulation is hampered by its strong anticoagulant activity, we were interested in evaluating modified heparins without such activity.

Heparins modified to inactivate the antithrombin binding site, with different molecular weight and degree of sulfation, were supplied to hepatic cell lines and mice to evaluate their potential modulation of hepcidin expression. We analysed their interference with the BMP/SMAD signalling, as well as serum hepcidin levels in mice by mass spectrometry.

Over 20 modified heparins were initially screened by evaluating their dose-dependent suppression of hepcidin expression before and after BMP induction. All of them showed a certain degree of anti-hepcidin activity, with two glycol-split molecules being as potent as classical unfractionated heparin. These two molecules suppressed BMP/SMAD signalling in HepG2 cells at pharmacological concentrations with maximum inhibition after 6 hours. In mice, treatments with 20 or 60 mg/Kg did not affect coagulation but strongly reduced liver pSMAD, hepcidin mRNA and serum hepcidin. Again, the maximum effect on liver hepcidin expression was observed 6 hours after the injection. This effect was observed also in conditions of high hepcidin caused by experimental inflammation or iron overload.

Some non-anticoagulant heparins have strong anti-hepcidin activity both in vitro and in vivo, and may represent promising hepcidin antagonist with potential therapeutic applications.

No relevant conflicts of interest to declare.